Determine flight capacity and dispersal ability of pea leaf weevil during spring and fall. Measure abiotic conditions (light and temperature) and host plant volatiles' effect on weevil flight capacity and dispersal ability. Determine metabolites used by weevils during active dispersal. Determine energy use effect during flight on subsequent reproductive potential.
This project is the first to directly test dispersal capacity of the pea leaf weevil, an invasive pest of field peas and faba beans around the world. A measure of dispersal capacity is needed to develop a provincewide monitoring system. The research shows that the pea leaf weevil dispersal by walking varies between spring and fall activity periods. Weevils that emerge from overwintering sites in spring move longer distances at a higher speed than weevils that leave crops in the fall. Spring weevils may colonize crop fields a distance away from overwintering sites. Pheromone-trap placements to monitor weevil densities in the spring should be done over a broad area. Dispersal by walking also varies by weevil sex and the surrounding host odours. Therefore, local landscape features such as crop type is an important to consider in monitoring this invasive species. Monitoring weevil abundance as they move to overwintering sites in the fall may be easier because weevils walk shorter distances more slowly which reduces the perimeter of pheromone-based trap placement. Fall weevil monitoring should be done immediately after harvest because weevils in fall are more active and move longer distances without host plants. This study suggests that pea leaf weevils may be capable of feeding during the overwintering period because spring weevils are heavier than weevils entering overwintering, and this corresponds to the finding that spring weevils have a higher walking capacity than fall weevils. Malaise traps and pan traps capture weevils in the fall but are not effective in spring weevil monitoring. These findings are important in the development of a monitoring system to predict pea leaf weevil abundance which will minimize the cost of pea leaf weevil chemical control such as seed treatments prior to seeding.